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Traders serve as mediators between service providers and users. The
trader returns to a service requester by delivering a set of
suitable providers that satisfy the request. Because of the size and
complexity of distributed systems, one trader manages a certain part
of the whole set of providers only. To enlarge this restricted set
of potential service providers, a lightweight form of cooperation
(called interworking) between two or more traders was introduced.
Therefore, the main purpose of such cooperations was concerned with
quantitative aspects, neglecting the possibilities of more general
concepts of cooperation. A need for qualitative trader cooperations
arises. Traditional trader approaches focus upon the operational
interface of providers as a basis for type descriptions. But in
general, application users in an open electronic market require
mediation at different levels of abstraction. Suitable traders are
specialized in one of these levels. By combining these isolated
solutions, a qualitative trader cooperation can be achieved.
In the following, we take a closer look at type descriptions at
different levels of abstraction. Similarities will be discovered
that can be used to derive appropriate mappings. In particular we
demonstrate that ODP--types based on an arbitrary interface
definition language can be described in terms of conceptual graphs
that are used in knowledge--based trading. From this relationship, a
general type manager can be derived, coping with both type concepts.
As a consequence, the trading of operational interfaces and the
trading based on a knowledge representation scheme can be combined.
Together they exhibit a more powerful trading service by offering
different interfaces to different kinds of users.
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